A new theoretical formulation for bubble plumes is presented, which serves for the definition of a sophisticated three-dimensional (3D) numerical model. The theoretical/numerical model includes a treatment of turbulence via a k - epsilon model and a Large-Eddy Simulation (LES) approach. It is based on a double averaging procedure that accounts for: (a) the presence of a two-phase flow, and (b) its turbulent nature. The model also allows for the global simulation of phenomena of break-up and coalescence. This theory is employed in the derivation and justification of existing one-dimensional (1D), "integral" models. The approximations involved are clearly explicited and quantified. In this framework, 1D models appear for the first time as a special case of this broader theory. This fact is finally used in extending existing 1D models, now including turbulence and phenomena of break-up and coalescence. (Abstract shortened by UMI.).